In pressurised boiling water nuclear reactors, it is known to regulate the pressure of the primary circuit by means of a regulator assembly comprising a pressurised chamber.
When the density of the fluid circulating in the primary circuit drops significantly, and the fluid increases in volume, it is known from FR 2 051 868 for example to derive part of the pressurised fluid present in the primary circuit off towards a pressurised chamber comprising a volume of pressurised fluid and a gas overhead.
To cause a reduction in pressure, part of the fluid intended to be added to the chamber is taken and sprayed in the form of droplets into the gas overhead of the chamber.
The formation of droplets condenses part of the gas present in the gas overhead, which reduces the pressure of the fluid. Said pressurizer therefore provides efficient pressure regulation.
However, to cause the pressurizer described in FR 2 051 868 to operate, it is necessary to use a regulator comprising driven valves.
In particular, a first valve is used to regulate the quantity of fluid entering the pressurizer and at least one second driven valve is used to regulate the amount of fluid to be sprayed into the gas overhead. The pressure regulating device is therefore complex.
Having regard to the high number of mobile parts involved for regulation, the reliability of the system is thereby weakened. This is particularly critical for nuclear installations on-board submarines.
It is therefore one objective of the invention to provide a pressure regulating device for an installation operating under pressure with which it is possible to obtain regulation reliably and at low cost independently of any movement of the installation.
For this purpose, the subject of the invention is a device of the aforementioned type characterized in that the device comprises:                an intermediate fluid-distributing receptacle positioned between the feed pipe and the spray assembly, the intermediate receptacle being connected upstream to the feed pipe and comprising a fluid-evacuating sidewall delimiting at least one through orifice connected to the spray assembly; and        at least one fluid evacuation pipe for evacuating fluid towards the chamber and projecting into the intermediate receptacle opposite the sidewall.        
The device of the invention may comprise one or more of the following characteristics taken alone or in any possible technical combination:                it comprises a plurality of evacuation pipes projecting into the intermediate receptacle, at least two evacuation pipes opening at different heights into the intermediate receptacle;        at least two evacuation pipes projecting into the intermediate receptacle have different inner cross-sections;        the or each evacuation pipe is arranged in a central region of the intermediate receptacle, the intermediate receptacle comprising a peripheral region around the central zone into which the feed pipe leads;        it comprises means for adjusting the height of the or of each evacuation pipe projecting into the receptacle;        the sidewall delimits a plurality of through orifices distributed over the height thereof;        the total cross-section of the through orifices located above the or each evacuation pipe on the sidewall is different from the total cross-section of the through orifices located at the height of the evacuation pipe;        the sidewall delimits a plurality of through orifices distributed angularly around an axis of the intermediate receptacle;        it comprises a member distributing the fluid from the feed pipe, the distributing member being arranged opposite the feed pipe;        it comprises a bottom plate closing the sidewall downwardly, the feed pipe opening into the bottom plate or through the bottom plate;        the fluid spray assembly is arranged outside and around the sidewall, the spray assembly comprising a shower volume, each through orifice connecting the intermediate receptacle with the shower volume;        the spray assembly comprises a lower wall delimiting a plurality of droplet-forming lumens.        
Another subject of the invention is a pressurised chamber, characterized in that it comprises a tank containing a liquid and a gas overhead, the chamber comprising a device such as defined above arranged in the tank, the spray assembly being arranged in the gas overhead of the tank, the evacuation pipes leading into the liquid.
A further subject of the invention is a power-producing installation comprising a source of energy, a heat exchanger and a primary fluid circulation circuit connecting the heat exchanger with the source, characterized in that it comprises a chamber such as defined above connected to the primary circuit.
The installation according to the invention may comprise one or more of the following characteristics taken alone or in any possible technical combination:                the installation is on-board a submarine.        
A further subject of the invention is a method for regulating pressure in a chamber, of the type comprising the following steps:                providing a device such as defined above;        bringing a fluid into the intermediate receptacle via the fluid feed pipe;        distributing the fluid brought into the receptacle to cause a first part of the fluid to pass through the or each through orifice, and a second part of the fluid through the or each evacuation pipe;        receiving the first part of the fluid in the spray assembly, and spraying the fluid in droplet form outside the device;        evacuating the second part of the fluid through the evacuation pipe to lead it into the chamber.        